title: Intraoperative magnesium administration does not improve neurocognitive function after cardiac surgery.
abstract: OBJECTIVE
  Neurocognitive decline occurs frequently after cardiac surgery and persists in a significant number of patients. Magnesium is thought to provide neuroprotection by preservation of cellular energy metabolism, blockade of the N-methyl-D-aspartate receptor, diminution of the inflammatory response, and inhibition of platelet activation. We therefore hypothesized that intraoperative magnesium administration would decrease postoperative cognitive impairment.
  
  
  METHODS
  After approval by the Duke University Health System Institutional Review Board, 389 patients undergoing cardiac surgery were enrolled in this prospective, randomized, double-blind, placebo-controlled clinical trial. Subjects were randomized to receive magnesium as a 50 mg/kg bolus followed by another 50 mg/kg infusion for 3 hours or placebo bolus and infusion. Cognitive function was assessed preoperatively and again at 6 weeks postoperatively using a standardized test battery. Mean CD11b fluorescence and percentage of platelets expressing CD62P, which are markers of leukocyte and platelet activation, respectively, were assessed by flow cytometry as a secondary outcome. The effect of magnesium on postoperative cognition was tested using multivariable regression modeling, adjusting for age, years of education, baseline cognition, sex, race, and weight.
  
  
  RESULTS
  Among the 389 allocated subjects (magnesium: n=198; placebo: n=191), the incidence of cognitive deficit in the magnesium group was 44.4% compared with 44.9% in the placebo group (P=0.93). The cognitive change score and platelet and leukocyte activation were also not different between the groups. Multivariable analysis revealed a marginal interaction between treatment group and weight such that heavier subjects receiving magnesium were less likely to have cognitive deficit (P=0.06).
  
  
  CONCLUSIONS
  Magnesium administered intravenously during cardiac surgery does not reduce postoperative cognitive dysfunction.
  
  
  BACKGROUND
  http://www.clinicaltrials.gov. Unique identifier: NCT00041392.
authors.affiliation: From the Departments of Anesthesiology (J.P.M., W.D.W., M.V.P., M.B., M.S.-S., M.F.N.), Neurology (D.T.L.), Psychiatry (J.A.B.), and Surgery (C.A.M.), Duke University Medical Center, Durham, NC; and Department of Anesthesiology, Sentara Cardiovascular Research Institute, Norfolk, VA (D.B.S.).
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Mathew
authors.forename: William D
authors.initials: WD
authors.lastname: White
authors.forename: David B
authors.initials: DB
authors.lastname: Schinderle
authors.forename: Mihai V
authors.initials: MV
authors.lastname: Podgoreanu
authors.forename: Miles
authors.initials: M
authors.lastname: Berger
authors.forename: Carmelo A
authors.initials: CA
authors.lastname: Milano
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Laskowitz
authors.forename: Mark
authors.initials: M
authors.lastname: Stafford-Smith
authors.forename: James A
authors.initials: JA
authors.lastname: Blumenthal
authors.forename: Mark F
authors.initials: MF
authors.lastname: Newman
mesh_terms: D000368:Aged; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D003071:Cognition / Q000187:drug effects*; D003072:Cognition Disorders / Q000188:drug therapy / Q000209:etiology / Q000517:prevention & control*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007430:Intraoperative Care / Q000379:methods*; D008274:Magnesium / Q000494:pharmacology / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D018696:Neuroprotective Agents / Q000494:pharmacology / Q000627:therapeutic use*; D011184:Postoperative Period; D016896:Treatment Outcome
chemical_list: D018696:Neuroprotective Agents; D008274:Magnesium
keywords: blood platelets; cardiopulmonary bypass; cognition